3. Tutor Types

CTAT enables you to create two main types of tutors:
Example-tracing Tutors, which can be created without programming, but
require problem-specific authoring; and Cognitive Tutors, which require
building a cognitive model of student problem solving, but support
tutoring across a range of similar problems.

There are a few factors that may influence your decision regarding
which tutor type to build:

the complexity of the tutor problems (i.e., the problems that
students solve as they work with the tutor);

whether many problems of the same type need to be
developed;

how many alternative solutions paths exist for each
problem;

whether subtle ordering constraints exist on the steps within
the tutor problems;

whether later steps in a problem depend on earlier steps;
and

whether in-house expertise in AI programming is available to
develop a cognitive model.

If you are new to the process of creating a tutor, we recommend
that you start with an Example-tracing Tutor.

For more information on the different types of tutors, see the
Tutor
Types page on the CTAT web site.

3.1. Example-tracing Tutor

An Example-tracing tutor is based on a single problem
representation stored in a behavior graph (BRD, or behavior recorder
data, file). You create this graph by demonstrating problem-solving
steps with the student interface. (See Example-tracing Tutors for more on creating an
Example-tracing Tutor.)

By default, the following tools are shown when the
Example-tracing Tutor type is selected:

Behavior Recorder

The Behavior Recorder is the only tool required to create an
Example-tracing Tutor. In addition, you will need a student interface
(built in Java or Flash) in which to demonstrate behavior. In the
Behavior Recorder, you can generalize, annotate, and test you
graph.

3.2. Cognitive Tutor (Jess)

A Cognitive Tutor is based on a rule-based cognitive model of
student problem-solving knowledge (modeled in Jess). This cognitive
model is commonly applicable to various problems in the same domain.
You create a cognitive model by writing production rules that
characterize the variety of strategies and misconceptions students may
acquire. (Cognitive Tutors are sometimes are also called "Production
Rule Tutors", a reference to the production rules you create when
modeling.)

During problem solving, the Cognitive Tutor follows the student
in a process called model-tracing. In model-tracing, the tutoring
system maintains a model of problem solving that is 'traced'
(compared) against the student's actions. Feedback during
problem-solving is given based on current state of the model (also
called working memory) and the rules that represent student cognition
and action.

By default, the following tools are shown the Cognitive Tutor
(Jess) type is selected:

3.3. Cognitive Tutor (TDK)

Caution

A Cognitive Tutor (TDK) is a tutor based on the TDK (Tutor
Development Kit) production rule language. This tutor type requires
access to a LISP rule engine, which is not included with CTAT.

The TDK modeling language was used to develop the Algebra and
Geometry Cognitive Tutors.

3.4. Simulated Student

Simulated Student, or Sim St, is a CTAT module that learns
cognitive skills from model solutions demonstrated by human
problem-solvers.

Using Sim St, an author demonstrates solutions to problems in a
domain using a student interface connected to CTAT. The Simulated
Student observes those demonstrations and generates a set of Jess
production rules that replicate the problem-solving steps
demonstrated. These production rules are generalizations of the
observed behavior. If these generalizations are correct—i.e., are
correct implementations of the actual task that is being taught—then
they can be added to the cognitive model as correct rules. If the
generalizations are incorrect but "plausible" (in the sense that a
student might adopt the incorrect conception), then they can be added
to the cognitive model as buggy rules. Both correct and buggy rules
would form the cognitive model of a Cognitive Tutor, allowing the
tutor to perform its usual functions, namely, model tracing and
scaffolding.

Access to Simulated Student functions can be found on the CTAT
menu Sim. St.